Condenser and method of condensing



Jan. 15, 1952 E. B. HERSHBERG ETAL CONDENSER AND METHOD OF CONDENSINGFiled Oct. 6, 1947 INVENTORS:

EMANUEL E1. HERSHEIERE,

AususT I- RYER Patented Jan. 15, 1952 2,582,250 CONDENSER AND METHOD orCONDENSING Emanuel B. Hcrsbberg, West Orange, N. J., and August I. Ryer,New York, N. Y., assignors to Scliering Corporation, Bloomfield, N. J.,a corpartition of New Jersey Application October 6, 1947, Serial No.778,168

7 Claims. (Cl. 62-172) This invention relates to a lyophilizingcondenser and to a method of condensing.

Lyophilization is the process of preparing in dry form substances,particularly biological substances and the like, such as blood plasma,antitoxins, toxins, and serums, by removing the water content thereof atlow temperatures under high vacuum. Typically, the substance remains inthe frozen state'during the dehydration process as a result of thecooling effect of the evaporation of water under high vacuum.

Lyophilizing systems commonly include alow temperature condenser in theline leading from the zone in which water vapor is removed from thefrozen material to the vacuum pump. Because of the low temperature andpressure maintained in the condenser, the water vapor deposits upon thecondensing surfaces in the form of ice. The deposited film of icerapidly increases in thickness, and, because of its insulatingqualities, soon interferes materially with the efliciency of thecondenser.

Various ways have been devised for removing ice from the condensingsurfaces. In some prior systems the apparatus is shut down, the'ice onthe condensing surfaces is melted and the resulting water is removedbefore the apparatus can be returned to service. In other prior systems,the ice is continuously removed from the condensing surfaces bymechanicallyoperated blades that scrape the ice from the condensingsurfaces.

An object of the present invention is to provide a condenser that may becontinuously operated in a lyophilizing system for long periods of timewithout requiring shut-downs for the removal of ice.

Another object is to provide such a condenser wherein ice is removedfrom the condensing surfaces almost as soon as it is formed and is notallowed to build up to a thickness that would lower condenserefliciency.

Another object is to provide a lyophilizing condenser having no scrapershaft penetrating the walls of the condens( T and giving rise to leakageabout the shaft.

Other objects are to provide a condenser of the type in question that iseconomical and simple to manufacture and operate, that is highlyeflicient in operation, and that requires a minimum of attention andmaintenance.

Still another object is to provide a method of condensing substancesthat pass directly from the gaseous to the solid state wherein thecondensed solid material is readily removed from the condensingsurfaces.

In accordance with the invention, the condenser typically includes acondensing chamber, means providing flexible condensing surfaces exposedto gas within said chamber, gas inlet means and gas outlet meanscommunicating with said chamber, and means for flexing said condensingsurfaces.

In an illustrative embodiment, the condenser takes the form of a devicewherein a metallic Sylphon bellows provides a portion of the walls ofthe condensing chamber and also provides the flexible condensingsurfaces. The bellows is flexed by mechanical means to break the icefrom the interior walls of the bellows. A sump for receiving the flakeice is positioned below and in communication with the bellows. Conduitmeans leading gas, principally water vapor, from the evaporator orsublimer extends into the bellows and a conduit connects the sump withthe evacuating device.

The foregoing and other aims and advantages of the invention will be inpart apparent and in part pointed out in the following description ofone embodiment as shown in the accompanying drawing wherein the singlefigure is a vertical sectional view of a lyophilizing condenserembodying the principles of the invention.

Referring to the drawing, the condenser shown has a main cooling jacketI!) having double side walls II and I2 including therebetween theinsulating layer IS. The side walls of the jacket are supported upon abase plate It having a central opening IS. A Sylphon bellows I6 iswelded to the base plate about the opening IS. The bellows is preferablyof metallic construction and is closed at the top. In the space I!between the bellows l6 and the jacket ill a refrigerating liquid,preferably one having a temperature of 40 C. or lower, is received forthe purpose of cooling the bellows. Refrigerating liquid is introducedinto the space I I through the inlet pipe 33 and overflow therefromleaves through the outlet pipe 32. The jacket is provided with a coverl8 which may be of insulating material to minimize absorption of heatfrom the outside. A manhole 36 is provided in the cover 28.

Secured to the underside of the base plate 14 by means of bolts I9 isanother similar plate 20. A gasket may be pressed between the plates toinsure a gas-tight fit. The lower plate 20 has a central opening 2| thatregisters with the opening 15 ofthe base plate It. A sump or icereceiver 22 is secured by a gas-tight joint to the plate 20 and acooling jacket 23 surrounds the sump and is adapted to maintain arefrigerant 24 in contact with the sump. Refrigerant is circulatedthrough the cooling jacket 23, it being admitted through inlet 35 anddischarged through outlet 34. The sump may be provided with a man-hole25 through which accumulated ice may be removed.

Gas from the evaporating zone is introduced to the condenser throughinlet pipe 26 that passes through the neck of the sump'and is bentupwardly and extended axially into the bellows is to a point near thetop. The gas outlet pipe 21 is connected to the evacuator andnon-condensed gas leaves the apparatus through this pipe.

A mechanical device is advantageously employed for .flexing andsupporting the bellows in the illustrated embodiment, but it will beevident to those skilled in the art that other suitable flexing devicesmay be employed within the teachin of the present specification. Theflexing device shown includes a rod 28 welded to the top of the bellowsand extending through a hole in the jacket cover l8. A pitman 29connects the rod 28 with a crank 30 rotating on shaft 3| to impart avertical oscillating motion to the bellows l6.

In operation, the jackets l and 23 are filled with refrigerant, thecrank 30 is rotated, and the evacuator, connected to pipe 21, draws gasfrom the evaporator, connected to pipe 26, through the apparatus in thedirection of the arrows. It will be understood that the vacuum pump isof sufflcient capacity to maintain a very low absolute pressure in thecondenser, such pressure preferably being less than 2 or 3 mm. ofmercury and even being less than 1 mm.

Water vapor from the inlet pipe impinges on the inner flexing walls ofthe bellows and condenses thereon in the form of a film of ice. Beforethe film of ice can develop a substantial thickness, the flexing of thebellows cracks the film and exfoliates thin laminae of ice which dropinto the sump 22, thus continuously exposing fresh surfaces for thecondensation of additional water vapor. The sump 22 may be cleaned asnecessary through the manhole 25.

The flexible condensing surface of the apparatus of the presentinvention may take other desirable forms. For example, a flexible coiledpipe through which refrigerant is circulated may be used as a condenser.Also, other means than is shown may be employed to flex or vibrate thecondenser such as electrical, magnetic, or fluid flexing means.

From the foregoing description it will be seen that the presentinvention provides a condenser for use in low temperature, high vacuumdrying systems that has high efliciency and excellent heat transfercharacteristics and wherein the ice removal problem is solved in a verysatisfactory manner.

We claim:

1. A condenser for low temperature, high vacuum condensation whichcomprises a substantially closed flexible envelope providing acondensing chamber sealed with relation to the external atmosphere andhaving an internal condensing surface, said envelope being constructedand arranged to substantially maintain its shape under a pressure dropof at least about one atmosphere, thereacross, means providing a sumpcommunicating with said envelope, gas inlet and gas outlet meanscommunicating with said en velope, means for cooling said envelope, and

means external to said envelope for flexing said envelope.

2. A lyophilizing condenser comprising a substantially closed bellowsproviding a condensing chamber sealed with relation to the externalatmosphere, said bellows being constructed and arranged to substantiallymaintain its shape under a pressure drop of at least about oneatmosphere thereacross, sump means communicating with said chamber, gasinlet and gas outlet means communicating with said bellows, a jacketsurrounding said bellows for the reception of a cooling medium, andmechanical means external to said bellows for flexing said bellows.

3. A lyophilizing condenser comprising a substantially closed bellowsproviding a condensing chamber sealed with relation to the externalatmosphere, said bellows being constructed and arranged to substantiallymaintain its shape under a pressure drop of at least about oneatmosphere thereacross, sump means communicating with said chamber, gasinlet and gas outlet means communicating with said bellows, a jacketsurrounding said bellows for the reception of a cooling medium, a jacketsurrounding said sump for the reception of a cooling medium, andmechanical means external to said bellows for flexing said bellows.

4. A lyophilizing condenser comprising a substantially closed bellowsproviding a condensing chamber sealed with relation to the externalatmosphere, said bellows being constructed and arranged to substantiallymaintain its shape under a pressure drop of at least about oneatmosphere thereacross, sump means communicating with said chamber, gasinlet and gas outlet means communicating with said bellows, means forcooling said bellows, and mechanical means external to said bellows forflexing said bellows.

5. A method of condensing substances that condense directly to the solidcondition which comprises conducting a gas comprising a substance thatcondenses directly to the solid state into contact with a flexiblecondensing surface in a confined zone maintained at sub-atmosphericpressure and at a temperature to deposit solid material thereon, andbreaking said solid material from said surface by changing the contourof said surface by the application externally of said zone of forcesexternal to said zone.

6. A condenser for low temperature, high vacuum condensation whichcomprises a substantially closed condensing chamber sealed with relationto the external atmosphere and having a flexible wall sectionconstructed and arranged to substantially maintain its shape under apressure drop of at least about one atmosphere thereacross, means forcooling the flexible wall section of said condensing chamber, gas inletmeans and gas outlet means communicating with said condensing chamber,and means external to said condensing chamber for flexing the flexiblewall section thereof.

'7. A lyophilizing condenser comprising a generally cylindrical verticalmetallic bellows, a member hermetically sealing the upper end of saidbellows, sump means hermetically sealed to the lower end of said bellowsand communicating with the interior of said bellows through an openingof substantially the same diameter as said bellows, a gas inlet pipeextending through and sealed in a wall of said sump, the inner end ofsaid pipe extending upwardly through said orifice and terminatingadjacent the upper end of said bellows, agas outlet pipe communicatingREFERENCES CITED The following references are of record in the file ofthis patent:

Number UNITED STATES PATENTS Name Date Copeman Sept. 20, 1932 ReichelDec. 29, 1936 Hayes Aug. 2'7, 1946

